Calcutta, Sept. 9: A day after Bengal had egg on its face because of the power failure at Salt Lake stadium during the India-Japan soccer encounter, the state experienced one of its worst power crises in recent memory.

A sudden shutdown of three 210-mw units at the state-run Kolaghat thermal plant last night, because of shortage of water required to generate steam to run the turbines, led to a combined shortfall of 800 mw in CESC and state electricity board areas during the evening peak hour.

During the day, power minister Mrinal Banerjee appealed to industries not to consume electricity between 6 pm and 11 am. 'We are trying our best to sort out the problem. I have spoken to the Union power secretary and the NTPC (National Thermal Power Corporation) chairman,' he said.

As an emergency measure, he asked Durgapur Projects Limited to cut off industrial supply and divert about 100 mw to the state electricity board grid. 'This helped us bring down our anticipated shortfall in the board areas by about 100 mw,' said an official.

The shortfall in the CESC-fed areas in Calcutta and its neighbourhood stood at 230 mw. In the districts, the deficit was about 570 mw. The board could not supply more than 130 mw to the CESC grid when 350 mw was sought.

'The situation is likely to remain grim for the next two days,' a senior power department official said.

Power cuts have been plaguing the state for the past few weeks following a drop in generation by the state-run units and poor supply from the NTPC plants at Farakka in Murshidabad and Talcher in Orissa. The shutdown of three Kolaghat units since last night compounded the situation.

In CESC-served areas, power cuts ranged between one-and-a-half and two hours while in the districts the blackouts continued for six-seven hours.

Trying to explain the generation setback, officials said water from the Roopnarayan river stopped flowing into a canal that brings it to the Kolaghat plant on Tuesday night because of heavy siltation.

'We started our own small dredger immediately to cut a channel to ensure the flow of water into our canal. But it did not help. We waited for the high tide'.but for the first time, water did not flow into our canal during high tide in mid-monsoon,' said S. Mahapatra, the managing director of West Bengal Power Development Corporation, which handles generation at the state-run units.

He said a bigger dredger has been requisitioned from a Calcutta Port Trust contractor and it is expected to reach by Saturday.